'Injured' Nishikori rules himself out of Shanghai Open

World number five Kei Nishikori has withdrawn from this week's Shanghai Rolex Masters due to an injury to his left gluteal muscle.

The 26-year-old sustained the injury during his second round clash against Portugal's Joao Sousa at the ongoing Japan Open and was eventually ruled out of the tournament.

While confirming the news, a disappointed Nishikori said that he needs at least 10 days rest and heavy rehabilitation to recover fully from his buttock muscle injury.

"I am so disappointed to have to pull out of the Shanghai Masters.The doctor is recommending at least 10 days rest and heavy rehab. It's disappointing for me to miss Shanghai as playing in Asia is a huge honour and pleasure for me," the Japanese sensation was quoted as saying by Sport24.

Nishikori, who clinched his only title this year at Memphis Open in February, will now return to his training base in Florida to undergo rehabilitation ahead of the next month's ATP World Tour Finals in London.